| aicra |

Aicra is a self-working REST API engine coded in Go that allows anyone to create a fully featured API. It features type checking, authentication management through middlewares, file upload, rich argument parsing (i.e. url slash-separated, urlencoded, form-data, json), nested routes, project compiler (i.e. aicra), etc.

All the REST API management is done for you, you just need to implement :

• the controllers
• the middlewares (to manage authentication, csrf, etc)
• the type checkers to check if input arguments follows some rules

There is 2 drivers that lets you implement these features in Go or whatever language.

This framework is based over some of the following concepts.

concept	explanation
meaningful defaults	Defaults and default values work without further understanding
configuration driven	Avoid information duplication. Automate anything that can be automated without losing control. Have one configuration that summarizes the whole project, its behavior and its automation flow.

A working example is available here

Table of contents

• I. Installation
  • 1. Download and install the package
• II. Setup a project
  • 1. Configuration
  • 2. Controllers
  • 3. Middlewares
  • 4. Custom types
• III. Build your project
• IV. Main
• V. Change Log

I. Installation

You need a recent machine with go installed.

This package has not been tested under the version 1.10.

1. Download and install the package

go get -u git.xdrm.io/go/aicra/cmd/aicra

The library should now be available locally and available for your imports. Moreover, the project compilet have been installed as the aicra command.

The executable aicra will be placed into your $GOPATH/bin folder, if added to your environment PATH it should be available as a standalone command in your terminal. If not, you can simply run $GOPATH/bin/aicra to use the command or create a symlink into /usr/local/bin for instance.

II. Setup a project

The default project structure for aicra is as follows :

├── main.go          - entry point
|
├── aicra.json       - server configuration file
├── api.json         - API configuration file
|
├── middleware       - middleware implementations
├── controller       - controller implementations
└── type             - custom type checkers

1. Compilation configuration

The aicra.json configuration file defines where are located your controllers, type checkers, and middlewares ; also it contains what driver you want to use, you have 2 choices :

1. plugin - for Go implementations
2. generic - for any language implementation (uses standard input and output)

field	description	example value
root	The project folder path	./some-path
driver	The driver to use for loading controllers, middlewares and type checkers	plugin orgeneric
types.default	Whether to load default types into the project	true, false
types.folder	The folder (relative to the project root) where type checkers' implementations are located	./type
controllers.folder	The folder (relative to the project root) where controllers' implementations are located	./controller
middlewares.folder	The folder (relative to the project root) where middlewares' implementations are located	./middleware

A sample file can be found here.

2. API Configuration

The whole project behavior is described inside the api.json file. For a better understanding of the format, take a look at this working template. This file defines :

• resource routes and their methods
• every input for each method (called argument)
• every output for each method
• scope permissions (list of permissions you can compose)
• input policy :
  • type of argument
  • required/optional
  • default value
  • variable renaming

3. Controllers

Controllers implement Get, Post, Put, and Delete methods, and have access to special variables surrounded by underscores :

• _HTTP_METHOD_ the request's HTTP method in uppercase
• _SCOPE_ the scope filled by middlewares
• _AUTHORIZATION_ the request's Authorization header

Also special variables found in the return data are processed with special actions :

• _REDIRECT_ will redirect to the URL contained in the variable

Plugin driver

For each route, you'll have to place your implementation into the controller folder (according to the aicra.json configuration) following the naming convention : add /main.go at the end of the route.

Example - /path/to/some/uri will be inside controller/path/to/some/uri/main.go

Exception - / will be inside controller/ROOT/main.go

A sample directory structure is available here.

Each controller must implement the git.xdrm.io/go/aicra/driver.Controller interface. In addition you must declare the function func Export() Controller to allow dynamic loading of your controller.

Generic driver

This is the same as with the plugin driver but instead of without /main.go at the end.

Example - /path/to/some/uri will be inside controller/path/to/some/uri where the uri file is an executable.

Exception - / will be inside controller/ROOT.

A sample directory structure is available here.

4. Middlewares

In order for your project to manage authentication, the best solution is to create middlewares, there are programs that updates a Scope (i.e. a list of strings) according to internal or persistent (i.e. database) information and the actual http request. They are all run before each request is forwarded to your controller. The scope are used to match the scope field in the configuration file and automatically block non-authenticated requests. Scopes can also be used for implementation-specific behavior such as CSRF management. Controllers have access to the scope through the variable _SCOPE_.

Plugin driver

Each middleware must be directly inside the middleware folder (according to the aicra.json configuration).

Example - the 1-authentication middleware will be inside middleware/1-authentication/main.go.

Note - middleware execution will be ordered by name. Prefixing your middlewares with their order is a good practice.

A sample directory structure is available here.

Each middleware must implement the git.xdrm.io/go/aicra/driver.Middleware interface. In addition you must declare the function func Export() Middleware to allow dynamic loading of your middleware.

Generic driver

This is the same as with the plugin driver but instead of without /main.go at the end.

Example - the 1-authentication middleware will be inside middleware/1-authentication where 1-authentication is an executable

A sample directory structure is available here.

5. Custom types

In your configuration you will have to use built-in types (e.g. int, any, varchar), but if you want project-specific ones, you can add your own types inside the type folder. You can check what structure to follow by looking at the built-in types. Also it is not required that you use built-in types, you can ignore them by setting types.default = false in the aicra.json configuration.

Each type must be directly inside the type folder. The package name is arbitrary and does not have to match the name (but it is better if it is explicit), because the Match() method already matches the name.

Plugin driver

Each type checker must be directly inside the type folder (according to the aicra.json configuration).

Example - the number type checker will be inside type/number/main.go.

A sample directory structure is available here.

Generic driver

This is the same as with the plugin driver but instead of without /main.go at the end.

Example - the number type checker will be inside type/number where number is an executable

A sample directory structure is available here.

III. Build your project

After each controller, middleware or type implementation, you'll have to compile the project. This can be achieved through the command-line builder.

Usage is aicra /path/to/your/project.

Usually you just have to run the following command inside your project directory :

aicra .

The output should look like

.

IV. Main

The main default program is pretty small as below :

package main

import (
	"git.xdrm.io/go/aicra"
	"net/http"
)

func main() {

    // 1. create the API from the configuration file
	server, err := aicra.New("api.json")
	if err != nil {
		panic(err)
	}

    // 2. listen to incoming http requests
	err = http.ListenAndServe("127.0.0.1:4242", server)
	if err != nil {
		panic(err)
	}

}

V. Change Log

• human-readable json configuration
• nested routes (i.e. /user/:id: and /user/post/:id:)
• nested URL arguments (i.e. /user/:id: and /user/:id:/post/​:id:​)
• useful http methods: GET, POST, PUT, DELETE
• manage URL, query and body arguments:
  • multipart/form-data (variables and file uploads)
  • application/x-www-form-urlencoded
  • application/json
• required vs. optional parameters with a default value
• parameter renaming
• generic authentication system (i.e. you can override the built-in one)
• generic type check (i.e. implement custom types alongside built-in ones)
• built-in types
  • any - wildcard matching all values
  • int - any number (e.g. float, int, uint)
  • string - any text
  • varchar(min, max) - any string with a length between min and max
  • <a> - array containing only elements matching a type
  • <a:b> - map containing only keys of type a and values of type b (a or b can be ommited)
• generic controllers implementation (shared objects)
• response interface
• devmode watcher : watch manifest, watch plugins to compile + hot reload them
• driver for Go plugins
  • controllers
  • middlewares
  • type checkers
• driver working with any executable through standard input and output
  • controllers
  • middlewares
  • type checkers
• project configuration file to select driver, source folders and whether to load default type checkers.
  • used to compile the project by the aicra command
  • used to create an API from aicra.New()